What Is "Nintendo Number"? (Clarification)

There is no single "Nintendo Number." You likely mean one of these:

• Nintendo Account ID / User ID: 16-digit number (e.g., 1234-5678-9012-3456) visible in Profile → User ID on Switch / accounts.nintendo.com. Used for friend adds (replaced Friend Codes).
• Friend Code (Legacy 3DS/Wii U): 12-digit XXXX-XXXX-XXXX. Found in Friend List app. Obsolete for Switch.
• Nintendo Network ID (NNID): Username (6-16 chars) for Wii U/3DS eShop/Miiverse. Merged into Nintendo Account.
• Serial Number (Hardware): On console bottom / box. Format: XAW12345678 (Switch), CW12345678 (3DS). For repairs/warranty.
• Customer Service Phone: Region-specific. US: 1-800-255-3700. UK: 0345 605 2492. See nintendo.com/consumer/contact.jsp.
• Game Code / Product Code: On cartridge label (e.g., CTR-P-AAAA-USA). Identifies exact ROM revision.

Clarify your context (Switch, 3DS, Wii, Support, Game ID) for exact answer.